No one can help feeling the way they do - feelings come unbidden. However, you CAN help acting on those feelings or putting them before your own inner sense of right and wrong. I'm not talking about some abstract sense of morals based on religion or convention, but about your personal ethics. What do YOU believe is the right thing to do here?
Our personal ethics are there for when it's HARD to do what we see as the right thing - not when it's easy. They're a guide in the darkness.
This is going to be an incredibly tough time for you emotionally and I can empathise.
When you are in love, it can feel so right. All the songs about 'how can something so wrong feel so right' suddenly make sense. Speaking from my own experience, it can be like stepping outside of reality - especially when the consequences aren't staring you in the face (i.e. no one knows about it).
Right now your feelings may be pulling you to and fro and making you dizzy. You can't necessarily trust them to help you through. You can only trust your sense of right and wrong - the things you believed before you were in this position. It's like walking along in the dark, and the only thing guiding you is a rope. If you let go of it, you will get lost. Trust yourself - trust your views from before you met him.
I think we are all a bit blind when we're in love. I once fell in love with a married man. At the time, he believed he loved me too. Perhaps he did. But I never lost sight of the fact that my feelings - and his - were less important than his family, my personal ethics and my self esteem. It wasn't an easy choice to cut all contact with him - it broke my heart to walk away. But it was the ONLY decision. There was no way of maintaining a friendship once we had talked so openly about our feelings.
If this man you love loves you too, he is not going to WANT to put you in a position where you can't tell friends about your love, you can't hold hands in the street and it's all about lies and deceit. If he is willing to put you through such horrible things, whatever is going on in his head, it isn't love.
Playing games with your feelings isn't love.